"Rollie the goalie" Melanson was selected in the third round, 59th overall by the New York Islanders in the 1979 NHL Entry Draft. Melanson played two and a half years of major junior hockey in the OHA with the Windsor Spitfires before being traded to the Oshawa Generals midway through the 1979-80 season. As a rookie in 1980-81, Melanson played in eleven games with the Stanley Cup champion Islanders posting an official 8-1-1 record with a 3.10 GAA behind starter Billy Smith. He was called up from the minors to replace Glenn Resch who was sent to the Colorado Rockies in February, 1981. He also started 51 games for the Indianapolis Checkers of the IHL, going 31-16-3 with two shutouts and a 2.57 GAA.

The following year Melanson primarily played in the minors but was used for 11 Islander games to Smith's 46 as the fans of Long Island got to celebrate their third consecutive Stanley Cup that spring. In 1982-83, Melanson started 44 games for New York, three more than Smith, and shared pair shared the Jennings Trophy which goes to the team with the lowest goals against average, but again found himself relegated to bench duty for the playoffs as the veteran Smith led the Islanders to their fourth Stanley Cup championship over the young Edmonton Oilers that spring. In 1983-84 starting duties with Smith were again shared, but Melanson's playing time was cut marginally to 37 games. The Islanders advanced to the Stanley Cup finals for the fifth year in a row, but were turned away in their quest for another title by the Oilers, who avenged their finals loss of a year earlier.

Melanson began the 1984-85 campaign with the Islanders, but with Billy Smith still around and a young Kelly Hrudey on the scene being groomed to take over the top spot, he was traded to the Minnesota North Stars for a first-round draft pick in 1995, which turned out to be Brad Dalgarno. His stay in Minnesota was short-lived as he was dealt to the New York Rangers but later that day was flipped to the Los Angeles Kings early in the 1985-86 season where he was the team's starting goaltender for two years.

He also played one game with the New Jersey Devils in 1990-91, signing as a free agent with the club on August 10, 1989. On September 20, 1991 he and Kirk Muller were traded to the Montreal Canadiens for Stephane Richer and Tom Chorske. Melanson started nine games with Montreal in 1991-92, and despite posting two shutouts in nine games, left the NHL soon after, realizing he was to see little playing time behind starter Patrick Roy.

Melanson played 15 games with the Brantford Smoke of the Colonial Hockey League in 1992-93 and also appeared in seven games for the Saint John Flames in the AHL in 1993-94 before retiring from professional hockey at the age of 33. He had the distinction of being the first person born in New Brunswick to play a game in goal in the NHL.